1. Field of the Invention
The present invention relates to a control method for shearing bars in a bar steel production line, and more particularly to a control method for shearing bars by which bar steel products of the same order lengths can be obtained most efficiently in shearing simultaneously to predetermined order lengths a plurality of bars obtained by dividing a bar steel blank.
2. Description of the Prior Art
A bar steel blank, which is a steel formed into a bar shape by rolling or the like, is in general produced continuously by a bar steel production line. Unlike hoops, strips, wire rods and the like, the bar steel blank continuously produced with a fixed cross-sectional shape and a fixed diameter by rolling or the like is sheared to predetermined order lengths by the steps of once dividing the bar steel blank into a plurality of bars by a flying shear, arranging the bars in parallel with each other and again shearing the bars to the order lengths by a cold shear, the process being accompanied by loss of bars.
An optimal shearing control in a bar steel line has been disclosed, for example, in "Enhancing the Shearing Yield of Bar Steel by Computer", Tetsu To Hagane (Journal of the Iron and Steel Institute), Vol. 67, No. 15 (1981), pp. 207-213, particularly in the section "4.1 Modeling for DP" on page 208. The article deals with the problem of obtaining an optimum shearing number of times for each of a plurality of bars obtained by dividing a rolled bar steel blank in order to minimize the loss generated in arranging the bars in parallel with each other and simultaneously shearing the arranged bars to the same lengths desired for bar steel products, and proposes a control method which solves the problem as follows.
Where
g.sub.1 (x)=loss generated when the i-th divided bar is sheared x times, and PA0 f.sub.K (x)=minimum loss expected to be generated from K divided bars,
the following functional equation is obtained according to the principle of optimization: ##EQU1## where N=number of bars divided
x=total number of times of parallel shearing PA1 M.sub.K =maximum number of times the divided bars can be sheared
Accordingly, the article concludes that optimal shearing control can be carried out on the basis of the solution.
The conventional optimal shearing control method, as described above, concerns optimal shearing for enhancing the yield with a minimum bar loss, and lacks considerations of optimal shearing on the basis of the shearing number of times in shearing collectively a plurality of bars arranged in parallel with each other and optimal shearing on the basis of shearing time.